P0672: Cylinder 2 Glow Plug Circuit

What it means

An electrical fault is present in the glow plug circuit for cylinder 2. The glow plug control module cannot drive this plug correctly — open circuit, short, or out-of-range resistance — so cylinder 2 is not pre-heated. On a cold start this causes hard starting, white smoke, and a misfire-like rough run until the engine warms. Causes: a failed glow plug, a broken supply lead to that plug, corrosion at the plug connector, or a faulty module output for cylinder 2.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The glow plug control module powers the glow plug in cylinder 2 to warm that cylinder for cold ignition. P0672 sets when the module detects an electrical fault in the cylinder 2 branch, including an open or short circuit or resistance outside the manufacturer’s specification. The code singles out cylinder 2’s plug circuit rather than cylinder 1 or the complete glow plug system.

Common causes

Most likely first.

1. Failed cylinder 2 glow plug
2. Open or shorted wiring to the plug
3. Corroded or loose connector
4. Glow plug control module output fault

Symptoms

• Glow plug warning light on (often orange coil symbol)
• Hard cold start or no start in cold weather
• White smoke from exhaust during warm-up

How to diagnose it

1. Save freeze-frame data and check whether other cylinder-specific glow-plug codes are present, which can indicate a shared supply or module issue.
2. Identify cylinder 2 from the vehicle’s service information and inspect its plug terminal, connector, and individual lead for corrosion, looseness, or damage.
3. With power isolated as directed by the manufacturer, measure the cylinder 2 glow plug and compare the result with the manufacturer’s specification.
4. Test the cylinder 2 lead for continuity and shorts, including at the plug connector and module connector.
5. If the plug and lead pass, check whether the glow plug module is commanding and delivering output on its cylinder 2 channel using the specified test method.
6. Confirm the repair by clearing the code and checking whether it returns during a cold-start cycle.

Common fixes

• Secure or clean the cylinder 2 glow plug connector.
• Repair an open, short, or damaged connection in the cylinder 2 lead.
• Replace the cylinder 2 glow plug if it fails the specified resistance or function test.
• Repair or replace the module’s cylinder 2 output if the plug and wiring are sound.

Can I keep driving?

You may be able to drive if the engine runs smoothly once warm, but cold starting can be rough and may produce white smoke. Avoid repeated cranking and have the circuit repaired before relying on the vehicle in cold conditions.